Beryllium alloy steels and articles of manufacture produced therefrom



Patented Jan. 22, 1946 BERYLLIUM ALLOY STEELS AND, ARTICLES OFMANUFACTURE PRODUCED THERE- FROM Enrique G. Touceda, Loudonville, andRalph P. De Vries, Menands, N. Y., assignors to Allegheny Ludlum SteelCorporation, a corporation of Pennsylvania No Drawing. Application July28, 1942, Serial No. 452,636

2 Claims.

The present invention relates to berylliumcontaining alloy steels and toproducts produced therefrom by casting, forging and rolling.

Magnet steels are characterized by the fact that they retain a largeproportion of the magnetism induced in them when placed in a magneticfield. By hardening them as much as possible their retentivity isgreatly increased. Steels containing chromium in various amounts up toabout 6% have been employed for magnets due to their relatively highretentivity. It is very difflcult, however, to produce chromium magnetsteels containing chromium in the indicated range in rolled form with acoercive force (He) of 60 or more and in any event it is essential thatspecial pre'- cautions be taken in the processing and hardening thereofto produce optimum coercive force values. In addition to this, suchmagnet steels do not have 9, BH value as high as is desired and thesefacts coupled with the necessity of using relatively high carbonat leastabout .90% and the lack of hardness and ductility as determined byRockwell Cone hardness tests and transverse bending tests, respectively,have left the chromium magnet steel situation in a relativelyunsatisfactory condition. Therefore, the industry is still seeking forimproved magnet steels which are not only simple and inexpensive toproduce but which have better magnetic and physical characteristics thanthose heretofore available.

One of the objects of our present invention is to produce magnet steelswhich overcome the defects and disadvantages outlined above and whichhave additional advantages by virtue of their unusual composition.

Another object of our invention is to produce magnet steels modified bythe incorporation therein of a small amount of beryllium andcharacterized by exceptionally desirable magnetic and physicalproperties.

A further object of our invention is to produce magnet steels which, inaddition to iron and the usual impurities in common amounts, containchromium and a relatively small amount of carbon and beryllium inapproximately the amounts hereinafter specified.

A still further object of our invention is to produce a beryllium alloysteel suitable for magnets and other commercial articles of manufactureand which, as hereinafter more fully set forth, is characterized byexcellent magnetic properties, by greater hardness and strength and bybetter fluidity when in the molten state than known magnet steels.

A still further object of our invention resides in the production ofmagnet steels and steels adapted for various other commercial productswhich are especially characterized by the fact that they contain, inaddition to iron and the usual impurities in common amounts, a carboncontent which may range from about .10% to about 1.25%, a chromiumcontent which may range from about 1% to about 8%. and a small amount ofberyllium which is always under 1% and which preferably ranges fromabout .03% to about 17%.

Other and further objects and advantages will be understood by thoseskilled in this art or will be apparent or pointed out below.

Our present invention is predicated upon the discovery that markedlysuperior properties can be imparted to alloy steels by the incorporationtherein of a small amount of beryllium (less than 1%). This berylliumaddition confers new and highly valuable magnetic properties on ourcompositions thus rendering them particularly adapted for employment inthe production of permanent magnets. The beryllium addition has otherunexpected and valuable eflects and in particular such are manifested bythe ability materially to reduce the amount of carbon employed, thusavoiding the processing difllculties accompanying the use of relativelyhigh carbon contents; by the imparting of materially greater hardness,as determined, for example, by Rockwell Cone hardness tests; byincreasing the strength of the compositions, as determined by transversebending tests, and hence by increased ductility and by endowing thematerial when in the molten state with a substantially improvedfluidity, thus facilitating casting operations.

As above indicated, our present invention involves alloy steels which,in addition to iron and the usual impurities in common amounts, containcertain percentages of carbon, chromium and beryllium. In the practiceof our invention, carbon may be incorporated in our new steels to theextent of from about .10% to about 1.25% but in those cases in whichcarbon is employed for use in magnet steels it is essential that it bepresent in the amount of at least .70% and may range from that value upto and including the maximum specified. The chromium content of our newalloy steels ranges from about 1% to about 8%. The present day chromiummagnet steels, while generally satisfactory and extensively utilized,are difiicult to produce with optimum magnetic characteristics and,therefore, our present invention is concerned with bringing about animprovement in connection with this disadvantage. The

beryllium content of our new alloy steels is always les than 1% andpreferably ranges in amount from about .03% to about 37%. Our new steelsmay optionally contain from about .10% to about .50% of silicon and ofmanganese; The usual imout taking any special precautions in theprocess- 1 ing and hardening of such steels. This is not onl highlyadvantageous in connection with the use of these compositions butrepresents very definite economic and commercial advantages as well.

Table I, which follows, is illustrative of the improved magneticproperties characteristic of our new beryllium alloy steels:

BH value is considered to be the best criterion of the strength ofa'permanent magnet. It will be noted from the table that whereas theconventional chrome magnet steel 135-13 has 0. BH value of about500,000, composition M-43 responding'to our present invention andcontaining about 1 /2% less chromium but with a 20% beryllium, has a BHvalue of nearly 60,000. The BH values of the beryllium containingcompositions are considerably greater than those without beryllium andthe coercive force of uch compositions is in every case above 60, someof the coercive forces running above '70. Attention is also directed tothe fact that composition M-53 which, in addition to 2.12% of chromium,contains .45% of beryllium and 379% of tungsten, has a very goodcoercive force of almost 74 and a BH value averaging about 545,000, butnevertheless it is not as strong magnetically as composition M-57 whichnot only contains no tungsten but which also contains less than as muchberyllium. The M-53 composition is, however, appreciably strongermagnetically than composition T-233 which contains preierred amounts ofmolybdenum and tungsten but which has no beryllium content.

In producing the highest quality permanent magnet steels in accordancewith prior practices,

Table I 0 T [1011 0 mm o c1 01 M11 Mo w B0 1101011001 00100110 10......B. 11. BE

cone condition Rockwell (Asrolled) orge .00 1.04 .41 .00 00 .000 -01111,002 0,002 02.0 010,000

Cross section of rolled and hardened bars=1% x s0".

This table sets forth pertinent and important data concerning severalcompositions responding to our present invention as well as somecompositions which have been included for comparative purposes. Thefirst column in the table serves to identify the individual compositionstested. The next columns give the analyses of those compositions. Thenext succeeding column sets forth the Rockwell Cone hardness of eachcomposition in the as quenched condition. The next column sets forth thequenching and/or other conditions of each composition from which themagnetic properties in the four right-Hand columns of the Table werederived. The heading Bronx. indicates the maximum number of magneticlines of force induced in each test piece under the test conditions, B1-indicates residual induction after reversal of the magnetic field and H0indicates coercive force. The last column, with the heading BH, is theproduct of the residual induction (B1) and the coercive force (He), thevalues of BH being given as approximations only,

it has been considered essential to have at least .90% of carbonpresent. In connection with our present invention we have furtherdiscovered that the presence of beryllium even in very small quantitiesreduces the carbon requirements down to a minimum of about .70% whilestill making it possible to produce steels having magnetic values at'least equal to those of the beryllium-free chromium steels with thehigher carbon contents. This is a distinct commercial advantage becauseit permits ,both the steels themselves and the as well as'forprojectiles and many other purposes where ordinary chromium steels donotprovide that extra necessary margin of hardness and strength which isrequisite for many usages.

In order to determine the direct effect of varying percentages ofberyllium a number of compositions were produced which weresubstantially identical except for the beryllium content. Several suchcompositions and the important properties thereof are set forth in TableII, which erty of hardness retention has a valuable application toball-bearing and races.

In Table III a further interesting and important property (the strength)of cast chromium 5 beryllium steels is delineated:

Ml Hardf c1 Si Mn Be Bend Fp.sl l wellC l0 Degrees M-66 1.01 2.22 0.100.07 0.00 I 0 02,000 04 05 111-05-- .00 2.22 .25 .01 .40 0 01,000 04/05M-64 1.00 2.10 .20 .00 .20 0 00,000 04/00 M-67 .00 2.10 .08 .00 None 044,000 00/04 These four steels (M-64 to M-67, inclusive) were allquenched in oil from the same temperature and were all then tested intransverse. The expectation was that fully-hardened steels would breakprematurely and would consequently show wide variations in strength dueto lack of follows; ductility needed to develop their full strength.

Table 11.

As Magnetic to rtles M It Ascast quenched p m j 0 Cr 01 Mn .Be 00001550F.oil

(will 3 3 13...... -B, H. an.

2.10 .20 0.00 0.20 00 00 11,000 0,110 002 020,000 2.22 .25 .07 .40 40 0010,410 7,400 005 014,000 2.22 .10 .01 .00 54 02 10,112 0,0 0 05.0450,000 2.10 .00 00 None 40 00 11,108 1,001 51.0 400,000

Cross section of castland hardened bars 1%" x tic".

Referring to this table it will be appreciated that the compositionsthere included range from 0% beryllium (M-67)' to .60% beryllium (M-66).These compositions were tested in the as cast condition. In eachinstance a. straight bar 1%" x 1%" was cast in a permanent graphitemold. The cast bar containing .20% beryllium has the highest BH valueand possessed the greatest hardness in the as cast condition, whereasthe beryllium-free composition showed up poorest in both respects. Asquenched in oil at 1550 F., the beryllium-free composition has thelowest Rockwell Cone hardness value and the 20% and .40% berylliumcompositions show the best hardness values. Attention is furtherdirected to the fact that'the beryllium-free composition M-67 does notapproachin the cast condition the magnetic values obtainable in therolled and vantage in making castings by any method and therefore formanypurposes our alloy steels may be cast and hardened to high hardnessvalues and when they are 'to be used for magnets they have much betterproperties than rolled chromium magnet steels. These beryllium steelsboth in the as cast and in the as rolled condition retain their hardnessmuch longer after drawing to "higher temperatures than do the straightchromium steels without beryllium. This prop- The results shown in thetab.e, however. prove that the strength actually. developed in thetransverse bending tests is beneficially influenced in proportion to theberyllium content. In other words, the composition with the highestberyllium content gave the highest test results and the lowest testresults occurred with respect to that composition which contained noberyllium. As to the intermediate compositions, M-64 with a 20%beryllium is materially better than M-67 without beryllium but M-65 witha 410% beryllium was even better than M-64.

7 It will be observed and appreciated from what has preceded that theincorporation of even a very small amount of beryllium has a remarkableeffect upon the properties of the alloy steel to which the same has beenadded. A beryllium content of as little as about 03% is effective, theresults differing primarily in their extent and intensity 'irom thosecompostionscontaining larger percentages of beryllium. For many purposesthe beryllium content need not be more than .1 or 2% but the particularamount of upon the intended use of any given composition and thereforeupon the properties which that use predetermines. As will be noted,beryllium has the capacity to increase the hardness and strength ofalloy steels such as the chromium alloy steels, to impart unusuallyexcellent magnetic properties to compositions which are used the moltenstate, thus facilitating and expediting casting operations of all types.The new, useberyllium which should be employed depends iul andunexpected results of incorporating small percentages of beryllium(under 1%) in alloy steels in accordance with our present inventioncould not have been predicted on the basis 01 existing knowledge. Thepractice or our present invention not only produces products which aresuperior and commercially advantageous but it also results inimprovements in production operations and technique. a

The foregoing is intended as illustrative and not as limitative and,without departing from the scope and principles hereof, we may resort tovarious additions, omissions, substitutions and modifications. Theinvention is rather that defined by the appended claims.

Having thus described our invention, what we claim as new and desire tosecure by Letters Patent is:

l. A permanent magnet composed of an alloy steel consisting of fromabout 1 to about 8% chromium, from about .10 to about 1.25% carbon andberyllium from about .03 to about .70% with the balance all iron exceptfor the usual impurities in common amounts and characterized by 9. BHvalue 01' about 600,000 by a coercive force above 60 and by a Rockwellhardness value greater than a magnet made from a similar alloy steelwithout beryllium within such range. 1 2. A magnet cast from an alloyconsisting of approximately 1.00% carbon. chromium within the'range orfrom about 2.00% to about 4.00 beryllium within the range 01' from about0.03% to about 1.00%, silicon and manganese each within the range orfrom about 0.10% to about 0.50% and the remainder iron except for usualimpurities in common amounts.

ENRIQUE G. TOUCEDA. RALPH P. DE VRIES.

